FIG. 5 schematically illustrates input and output pin configurations of a prior art mask-type ROM chip, a piggyback-type chip, and an evaluator-type chip. Reference numeral 1 designates a package of the mask ROM chip, reference numeral 2 designates a package of the piggyback-type chip, and reference numeral 3 designates a package of the evaluator-type chip. On a surface of the piggyback-type chip package 2, there are mounted a plurality of program testing terminals 4 that are used to connect the EPROM to the piggyback-type chip package. The evaluator-type chip 3 has more pins than either the mask-type ROM chip package 1 or the piggyback-type chip package 2. The additional pins of the evaluator-type chip 3 are needed to connect pins such as a terminal for an external memory, a terminal for a control signal, and so on to the package of the evaluator chip 3. Accordingly, although packages 1 and 2 are the same relative to the physical placement of the pins, that is, pin arrangement, and also in the manner in which they are connected to the internal circuitry, that, is program pin configuration, package 3 is different from packages 1 and 2 in pin arrangement and pin configuration. Furthermore, the pin arrangement and configuration of package 2 allows the packages 1 and 2 to be loaded on a final product board. However, package 3 cannot be loaded on a final product board.
In the prior art, when the evaluation of a microcomputer is made by using the evaluator-type chip, as shown in FIG. 6, an interface board 6 is necessary because of the incompatibility of the terminals of the piggyback-chip 2 with those of the evaluator-type chip of FIG. 5.
Therefore, in the prior art, an interface board is required for use with the product board 5. The product board 5 and the interface board 6 are connected with a flat cable 7 which has connections at either end of the cable, the evaluator-type chip package 3 is mounted using the evaluator chip terminals at a predetermined position on the interface board 6. The evaluator-type chip package 3 and a development tool or insert kit emulator 8, which is a debugger, and the like are connected using a flat cable 9 having connectors at either end of the cable.
In the prior art, since the piggyback-type chip and the evaluator-type chip require different input and output signals, they are designed independently. Further, since the packages thereof are different as described above, packages of different types must be constructed, respectively. Among the various problems that result from the development of independent designs is that the program development requires much time, and the manufacturing cost is increased. Further, the evaluator-type chip cannot be directly incorporated into the board of the final product which has mounted thereon the microcomputer so that another interface board and so on must be provided as described above.
In view of this, it is desirable to provide, in accordance with the invention, a universal package which is fully compatible with the final product board and the evaluator-type chip to obviate the cumbersome arrangement of using an interface board because of incompatibility of the terminals of the piggyback-type chip and the evaluator-type chip. Therefore, the piggyback-type chip and the evaluator-type chip are not necessarily developed separately.